Cathode ray tube with electrode supported by strap-like springs



l967 T. M. SHRADER ETAL CATHODE RAY TUBE WITH ELECTRODE SUPPORTED BY STRAP-LIKE SPRINGS 2 Sheets-Sheet 1 Filed Nov. 5, 1964 40 mm m 4 VHO m5 K Ma w J N m %N CVY B %N\ 3 Q, N. 4 w Q Q J 3, 1967 T. M. SHRADER ETAL 3 2 477 CATHODE RAY TUBE WITH ELECTRODE SUPPORTED BY STRAP-LIKE SPRINGS Filed Nov. 5, 1964 I 2 Sheets-Sheet 2 INVENTORS 72km M SHEA/75? BY Gum/1v K. 540M215 J2.

United States Patent Ofiice 3,296,477 Patented Jan. 3, 1967 3,296,477 CATHODE RAY TUBE WTTH ELECTRQDE SUP- PORTED BY STRAP-LIKE SPRINGS Terry M. Shrader, Leacock, and Glenn R. Fadner, Jr.,

Landisville, Pa, assignors to Radio Corporation of America, a corporation of Delaware Filed Nov. 5, 1964, Ser. No. 409,190 8 Claims. (Cl. 313-85) This invention relates to cathode ray tubes and particularly to the structure and support for an electrode therefor wherein apertured spring support straps are attached to the electrode and disposed over a plurality of support studs for removably mounting the electrode.

In some types of cathode ray tubes, an electrode of substantially the same size as the phosphor screen of the tube is mounted closely adjacent to the screen. For example, the shadow mask cathode ray tube for producing images in color includes a multiapertured masking electrode which may be spaced about /2-inch from a mosaic phosphor screen. The commercially available RCA 21FBP22 is such a tube.

, The envelopes of tubes which have an electrode mounted adjacent to the screen usually include a shallow bowl-like glass faceplate panel sealed to a glass funnel member. The faceplate panel comprises a curved faceplate portion on which the phosphor screen is disposed and a peripheral sidewall portion. A plurality of studs are sealed into or onto the internal surface of the sidewall of the panel. The mask electrode is removably mounted on the studs by a plurality of strap-like springs which are attached to the mask and which have apertures therein into which the studs fit.

It is an object of this invention to provide an improved means for attaching the support springs to an electrode of a cathode ray tube.

It is also an object of this invention to provide an improved assembly of faceplate panel and shadow mask electrode for a cathode ray tube.

Another object of this invention is the provision of an improved mounting spring for a shadow mask electrode.

In accordance with the invention, an electrode such as described above is positioned within a faceplate panel and spaced from the faceplate thereof preferably by a spacer device interposed therebetween. The panel includes a plurality of suitable electrode support studs eX- tending inwardly therof. The electrode is mechanically connected to and supported by the panel by means of at least three spring elements each having an apertured end engaging one of the panel studs and having the other end attached to the electrode. At least one of the spring elements is engaged with and temporarily held by a hook and a mounting surface on the electrode during adjustment of the spacing of the electrode from the panel, and then attached to the electrode, as by welding. Either the surface of the spring element engaging the electrode mounting surface or the mounting surface is provided with an initial curvature which is convex with respect to the other surface, in order to obtain extended surface contact between the surfaces after assembly of the spring element with its stud and thus facilitate welding by mass production techniques. In this manner, the apertured spring elements are secured to the electrode assembly in precise alignment with their associated panel studs.

According to the prior art, often the studs are attached to a faceplate panel by the use of one jig and the support springs are attached to the mask electrode by the use of a different but related jig. The resulting tolerance of fit of the mask on the studs and the tolerance of the maskto-screen spacing is accordingly determined by the additive tolerance of the two jigs. The present method avoids the inaccuracies of such additive tolerances. The studs themselves are used as the locating jigs for securing the apertured spring elements relative to the mask electrode, thereby providing a custom fit between the mask electrode and studs. The use of the spacer device insures an accurate spacing of the mask electrode from the faceplate.

. In a tube wherein the mask electrode is supported on three studs (3-stud system), the inaccuracies of the prior art method of using two separate jigs may not be detrimental to the fit of the mask on the studs. However, it will be detrimental to an accurate establishing of maskto-screen spacing. In a tube wherein the mask electrode is supported on four studs (4-stud system) the inaccuracies of the 2-jig prior art method will be detrimental to both the fit of the mask on the studs and to the mask-toscreen spacing. The improved accuracy of fit between the mask electrode and the studs obtained by the new method is therefore especially advantageous in a 4-stud system such as has been proposed for a shadow mask cathode ray tube having a rectangularly shaped faceplate and mask electrode.

With the general type of spring-stud arrangement described herein, a 3-spring mask can always be fitted onto its 3-stud panel even though, due to manufacturing tolerances, the spring aperture array and the stud array are not identically disposed. This is because the mask can be shifted and rotated slightly until each of the three spring apertures is in alignment with its associated stud. Furthermore, the three springs will be received on the three studs with the mask in only one position. That is, a 3-point support arrangment of three springs on three studs determines a unique position of the mask relative to the panel. This is true not only for a 3-stud support system, but also for three of the four supports of a 4- stud support system. Thus, in a 4-stud system, the fourth spring and the fourth stud must be positioned so that they mate precisely with each other when the mask is in the unique position determined by the other three supports. Manufacturing tolerances of the prior art methods described above do not permit such precise positioning to be readily obtained.

In the drawings:

FIG. 1 is a plan view of a cathode ray tube faceplate panel and apertured mask electrode together with a spacing fixture utilized in securing the apertured spring elements to the mask electrode assembly;

FIG. 2 is a sectional view taken along line 22 of FIG. 1;

FIG. 3 is an enlarged sectional view of a portion of the device of FIGS. 1 and 2 taken along line 3-3 of FIG. 2;

FIG. 4 is a perspective view of the spring support of FIG. 3;

FIG. 5 is a sectional view taken on line 5-5 of FIG. 3;

FIGS. 6 and 7 are plan and side views, respectively, of an alternative mounting plate;

FIG. 8 is a plan view of an electrode frame and panel side wall with a mounting spring and another type of mounting plate assembled therebetween;

FIG. 9 is a side view of the frame and mounting plate of FIG. 8; and

FIGS. 10 and 11 are sectional views similar to FIG. 3 of two other modifications.

With reference to the drawing, a cathode ray tube glass faceplate panel 10 comprises a generally rectangular faceplate 12 and a sidewall 14 extending from the periphery of the faceplate. The faceplate 12 is preferably curved, e.g., with an approximately spherical contour, as is known in the art. A plurality of electrode mounting studs 16 extend from the interior surface of the panel sidewall 14. The studs 16 may be bonded to the surface of the sidewall with, e.g., a glass frit, or they may be embedded in the sidewall by a conventional glass-tometal seal. In a preferred arrangement, four studs are provided, one near each of the mid-points of each of the two long sides 18 of the sidewall 14 and the two short sides 20 of the sidewall 14. Each stud 16 (FIGS. 3 and 4) comprises a cylindrical base 21 and a frusto-conical tip 22.

A shadow mask electrode 24, mounted within the faceplate panel 10, includes a frame member 26 and a masking member 28. The frame 26 comprises a generally rectangular loop-shaped rim having an L-shaped cross section. The masking member 28 comprises a shallow bowl-like multiapertured sheet of metal mounted across the frame 26. The masking member 28 has a surface contour which approximately matches the surface contour of the faceplate 12, for example, as described in US. Patent 3,109,116, issued to D. W. Epstein et al., on October 29, 1963.

A plurality of support springs 29 are attached to the electrode 24 and support it on the studs 16. As best shown in FIGS. 3 to 5, each of the support springs 29 has one end 33 attached to the side of the frame 26. The other end 34 of the spring is off-set outwardly from the side of the frame and provided with a stud-receiving aperture 31. The off-set may be provided by suitably bending the springs 29 along a line 32 thereacross. The springs are located so that their apertures 31 receive the frusto-conical tips 22 of the studs 16 to remov ably mount the mask electrode 24 within the panel 10. The mask electrode 24 may be removed and/or re-mounted by depressing the support springs 29 toward the frame 26 and free of the studs 16. Each aperture 31 is preferably shaped to contact the stud tip 22 in three triangularly spaced locations. For example, the aperture 31 may include three inwardly projecting fingers 35 which are suitably shaped to mate with the stud tip 22.

Each of the springs 29 may be attached directly to the side of the frame 26. However, in order to provide means on the frame for permitting adjustment of the relative position of each spring 29 with respect to the frame 26, it is preferred to include, as a part of electrode 24, a mounting plate 36, having a hook or J-shaped end 37, attached to the frame 26 in position to receive the end 33 of each spring 29, and to frictionally engage the spring 29 with the 'hook 37 during adjustment of the position of the mask 28 relative to the faceplate panel 10. Each spring 29 is manufactured with the end portion 33 initially curved so that it is convex to the outer surface of the mounting plate 36.

In fabricating the assembly of panel 16 and mask electrode 24, the multiapertured mask member 28 is first mounted on the frame 26 according to known techniques. The plates 36 are then attached (such as by welding) flush against the outer peripheral surface of the frame 26 in a position and orientation so as to receive the springs 29 therein with the apertures 31 thereof disposed approximately opposite the studs I16. This mask-frame-plate assembly 28, 26, 36 (hereinafter referred to simply as the mask assembly) is then positioned on top of a spacer device 39 Within the faceplate panel 10, to accurately establish a desired mask-to-screen spacing. The panel may be oriented open-end-up as shown in FIG. 2 so that gravity urges the mask assembly 28, 26, 36 against the spacer 39 and the spacer against the panel 10.

The spacer device 39 includes a T-shaped member whose three arms 40, 40, 41 extend to adjacent to the panel sidewall 14. Spacer pads 42 are provided near the 4 ends of the arms 40, 40, 41 and extend therefrom to contact the faceplate 12. Mask-support brackets 44 are attached to the ends of the spacer arms 40, 40, 41 for receiving the mask assembly 28, 26, 36 in desired relationship with the face plate 12.

Other types or designs of spacer devices may be used in place of the spacer device 39.

If desired, the panel 10, spacer 39, and mask assembly '28, 26, 36 may be inverted, with the mask assembly 28, 26, 36 being supported and the panel 10 resting thereupon.

With the mask assembly 28, 26, 36 in position within the faceplate panel 10, the apertures 31 of the springs 29 are engaged with the stud tips 22 and then the ends 33 of the springs 29 are depressed and inserted into the hooks 37 of the plates 36. Alternatively, the springs 29 can be assembled by first inserting the ends 33 into the hooks 37 and then depressing the springs toward the frame 26 and engaging the apertures 31 with the stud tips 22. In such an arrangement, the spring action of the springs urges the apertures 31 against the studs 16 to keep them in place.

At this point of the fabrication procedure, the springs 29 are still free to move relative to the plates 36, and the mask assembly 28, 26, 36 and spacer device 39 are still free to be urged together and against the faceplate 12.

' Thus, in this condition, the operator now establishes a precisely desired spacing between the mask electrode 24 and the faceplate 12 and a precise alignment of the studreceiving apertures 31 of the springs 29 with the studs 16.

The springs 29 are then secured to the plates 36, as by a suitable welding thereof. It has been found preferable to provide only a temporary tack weld at this stage. Then, with the completely assembled mask electrode 24 removed from the panel 10 (by depressing the springs 29) a more secure weld using larger equipment is provided. The reason for making the initial tack weld is that the larger welding equipment cannot be easily fitted into the available space between the frame 26 and panel sidewall 14 when the mask assembly 28, 26, 36 is disposed in the panel 10.

The above-described methods of attaching the spring apertured elements relative to the frame 26 may be used to secure either all of the support springs or any partial number of them, to the frame 26. For example, in a 4-stud panel, three support springs 29 may be secured to the frame by prior art methods. Then the mask-frame assembly with the three springs may be supported within the panel using the three existing springs. The fourth spring 29 is then secured to the frame 26 as hereinbefore described. In such a fabrication procedure, the spacing device 39 may, if desired, be dispensed with since the mask can be supported in place within the panel by the three existing springs during the securing of the fourth apertured spring element. Attachment of only one apertured spring by the new method will provide the custom alignment highly desired in positioning the fourth spring of a 4-spring mask electrode 24.

It has been found that if the end portion 33 of the spring 29 is initially flat or planar, the middle of this end portion 33 will usually bow out, away from the adjacent plate 36, when the spring is flexed to assemble it with the stud tip 22 and hook 37. This bowing out makes it difficult, in production line manufacture, to weld the end 33 to the plate 36 with suflicient rigidity without misaligning one of the four springs 29 with its stud 16. To avoid this bowing, the end portion 33 of any spring 29 which is to be Welded in place while being flexed against its spring action is manufactured with an initial curved set, with the center of curvature on the side of the spring 29 opposite the frame 26. The initial angle of the bend at 32 and the initial curvature are chosen so that the end portion 33 will not bow out from the plate 36 when the spring 29 is assembled with the plate 36 and stud 16. For example, satisfactory springs 29, for use in a 25 inch rectangular color picture tube, have been made of stainless steel with the following dimensions:

FIGS. 6 and 7 show an alternative mounting plate 46 which may be used instead of the plate 36 in FIG. 3. Instead of a single wide hook, the plate 46 has a narrow end hook 47 on one corner and a second hook 48 on the opposite side. Such a hook arrangement provides clearance which facilitates welding of the plate 46 to the frame, and the spring 29 to the plate 46.

The alternative mounting plate 50 shown in FIGS. 8 and 9 comprises a narrow strip 51 having end portions 52 and 54 offset a distance equal to the thickness of the strip. The end portions 52 and 54 have lateral extensions 56 and 58 that are welded at 59 to the side of the frame 26. The extension 56 has a further extension 60 which is offset from the frame 26, as shown in FIG. 8, to form a hook for receiving the curved end 33 of a mounting spring 29. After assembly and adjustment of the mask to panel spacing, the spring 29 is welded, at 62 and 64, to the frame 26 and plate 50. This arrangement forms a very rigid mount for the mask frame 26 on the panel wall 14.

The end of the electrode mounting spring can be inserted in a hook formed in the mask frame itself, as shown in FIG. 10. The frame 66 is formed with an opening or slot 68 through which an offset end portion 72 of a mounting spring 70 is inserted. The portion of the frame underlying the end 72 of the spring corresponds to the hook 37 of the plate 36 in FIGS. 1-5. The portion of the spring 70 adjacent to the end 72 is initially curved as in the other embodiments, to permit assembly of the aperture 76 over the panel stud (not shown) Without bowing the spring 70 out from the frame.

FIG. 11 shows an embodiment in which the mounting spring is initially flat and the mounting plate is initially curved. A mounting plate 80 having a curved surface 82 and an end hook 84 is attached by welding at both ends to a frame 26. A mounting spring 86 having an initially flat base or mounting portion 88 is inserted into the hook 84 and depressed onto the curved surface 82 to engage the aperture 90 with the panel stud (not shown). The curved surface 82 could be an integral portion of the frame 26.

What is claimed is:

1. A cathode ray tube comprising a faceplate panel, at least three support studs extending from said panel, an electrode, and at least three mounting means attached to said electrode and having apertures receiving said studs for mounting said electrode in spaced relation to said panel; at least one of said mounting means comprising a mounting surface on said electrode, a strap-like support spring having an aperture at one end receiving one of said studs and a mounting surface at the other end engaging the outer periphery of said electrode, one of said mounting surfaces being initially curved convex to the other surface, a hook on said electrode for holding said surfaces in contact during assembly of said spring, said other end of said spring extending into said hook, and means for attaching said spring to said electrode independently of said hook with said surfaces in extended contact with each other in opposition to the resiliency of said spring.

2, A cathode ray tube comprising a faceplate panel, at

least three support studs extending from said panel, an electrode including a mounting frame, and at least three mounting means attached to the outside of said electrode frame and having apertures receiving said studs for mounting said electrode in spaced relation to said panel; at least one of said mounting means comprising a mounting surface on the outside of said frame, a strap-like support spring having an aperture at one end receiving one of said studs and a mounting surface at the other end engaging said frame mounting surface, one of said mounting surfaces being initially curved convex to the other surface, a hook on said frame for holding said surfaces in contact during assembly of said spring, said other end of said spring extending into said hook, and means attaching said spring to said frame independently of said hook with said surfaces in extended contact with each other in opposition to the resiliency of said spring.

3. A cathode ray tube as in claim 2, wherein said frame mounting surface is initially substantially flat and said spring mounting surface is initially curved.

4. A cathode ray tube as in claim 2, wherein said frame mounting surface is initially curved and said spring mounting surface is initially substantially flat.

5. A cathode ray tube comprising a faceplate panel, at least three support studs extending from said panel, a multiapertured mask electrode including a mounting frame and at least three mounting means attached to said frame and having apertures receiving said studs for mounting said electrode in spaced relation to said panel, at least one of said mounting means comprising a mounting plate attached to the periphery of said frame and including a hook portion and an adjacent mounting portion, a strap-like support spring having an aperture at one end receiving one of said studs and a base portion at the other end engaging said hook and mounting portion, one of said base and mounting portions having an initial curvature convex to the other portion, said base portion being welded to said plate in extended surface contact with said mounting :portion in opposition to the resiliency of said spring.

6. A cathode ray tube as in claim 5, wherein said base portion of said spring is initially curved relative to said mounting portion of said plate.

7. A cathode ray tube as in claim 5, wherein said mounting portion of said plate is initially curved relative to said base portion of said spring.

8. A cathode ray tube comprising a faceplate panel, at least three support studs extending from said panel, a multiapertured mask electrode including a mounting frame and at least three mounting means attached to said frame and having apertures receiving said studs for mounting said electrode in spaced relation to said panel, each of said mounting means comprising a mounting plate attached to the periphery of said frame and including a hook portion and an adjacent mounting portion, a straplike support spring having an aperture at one end receiving one of said studs and a base portion at the other end engaging said hook and mounting portion, one of said base and mounting portions having an initial curvature convex to the other portion, said base portin being welded to said plate in extended surface contact with said mounting portion in opposition to the resiliency of said spring.

References Cited by the Examiner UNITED STATES PATENTS 2,846,608 8/1958 Shrader 3 l385 2,922,063 1/1960 Haas 3 l392.5

JAMES W. LAWRENCE, Primary Examiner.

R. SEGAL, Assistant Examiner. 

1. A CATHODE RAY TUBE COMPRISING A FACEPLATE PANEL, AT LEAST THREE SUPPORT STUDS EXTENDING FROM SAID PANEL, AN ELECTRODE, AND AT LEAST THREE MOUNTING MEANS ATTACHED TO SAID ELECTRODE AND HAVING APERTURES RECEIVING SAID STUDS FOR MOUNTING SAID ELECTRODE IN SPACED RELATION TO SAID PANEL; AT LEAST ONE OF SAID MOUNTING MEANS COMPRISING A MOUNTING SURFACE ON SAID ELECTRODE, A STRAP-LIKE SUPPORT SPRING HAVING AN APERTURE AT ONE END RECEIVING ONE OF SAID STUDS AND A MOUNTING SURFACE AT THE OTHER END ENGAGING THE OUTER PERIPHERY OF SAID ELECTRODE, ONE OF SAID MOUNTING SURFACES BEING INITIALLY CURVED CONVEX TO THE OTHER SURFACE, A HOOK ON SAID ELECTRODE FOR HOLDING SAID SURFACES IN CONTACT DURING ASSEMBLY OF SAID SPRINGS, SAID OTHER END OF SAID SPRING EXTENDING INTO SAID HOOK, AND MEANS FOR ATTACHING SAID SPRING TO SAID ELECTRODE INDEPENDENTLY OF SAID HOOK WITH SAID SURFACES IN EXTENDED CONTACT WITH EACH OTHER IN OPPOSITION TO THE RESILIENCY OF SAID SPRING. 